1. Field of the Invention
This invention relates to a method for recording and reproducing an electron beam image information, and more particularly to a method for recording and reproducing an electron beam image information, which enables an electron beam image transmitted through or reflected from a sample to be recorded and reproduced with high sensitivity and high accuracy.
2. Description of Prior Arts
There have been known electron microscope devices or electron diffraction devices in which a sample is irradiated with an electron beam under vacuum to obtain a transmitted electron beam image or a reflected electron beam image. In the electron microscope device, the diffraction pattern of a sample is formed on the back focal plane of a objection lens by an electron beam transmitted through the sample, and the enlarged image of the sample is formed by the interference of a diffracted beam. Thus, if the enlarged image is projected by means of a projection lens, the enlarged image (scattered image) of the sample can be observed. Further, if the diffraction pattern on the back focal plane is projected, the diffraction pattern of the enlarged sample can be observed. If an intermediate lens is provided between the objective lens and the projection lens, the enlarged image (scattered image) or the diffraction pattern can be optionally observed by adjusting the focal distance of the intermediate lens. In the electron diffraction device, there are a reflection method wherein the surface of a sample is irradiated with an electron beam and a reflected diffraction beam is recorded to obtain a diffraction pattern, and a transmission method wherein a diffracted beam transmitted through a sample is recorded to obtain a diffraction pattern.
In order to convert the enlarged image or the diffraction pattern (both are hereinafter referred to as electron beam image) into a visible image, there are used methods wherein a photographic film is arranged on an image formation plane to record the electron beam image thereon, or an image intensifier is provided to produce the intensified projection of the electron beam image. However, the photographic film has disadvantages in that the film is not sensitive enough to an electron beam and its development is not easy. The image intensifier has also disadvantages in that the sharpness of the image is poor and the image is liable to have distortion.
The electron beam image recorded as described above is generally subjected to image processings such as gradation processing, frequency intensifying processing, density processing, substraction processing and addition processing; the reconstruction of a three-dimensional image by Fourier analysis method; image analysis for the measurement of particle diameter and forming binary image; and diffraction pattern processing (crystal information, clarification of lattice constant, transition, lattice defect, etc.) to make the image more easy to observe. Such processings have been conducted, and a visible image obtained by developing the photographic film has been read by means of a microphotometer and converted into an electric signal which has been then subjected to A/D conversion and processed by a computer. The image has been conventionally subjected to the above-described complicated operation.